Introduction
IgG4-related disease is an autoimmune disease of unknown etiology in
which IgG4-positive plasma cells infiltrate the body organs and cause
swelling, nodules, and hypertrophic lesions in target organs.
Approximately 20% and 5% of patients have vision loss and visual field
defects, respectively1).
Two major pathological conditions can cause optic neuropathy in this
disease: compression or encasement of the optic nerve by an enlarged
tissue in the orbit and compression of the optic chiasm by the enlarged
pituitary gland. In the former case, compression or encasement of the
optic nerve by the enlarged external ophthalmic muscle or localized or
diffuse tissue proliferation in the orbit has been
reported2). The latter is a condition that can develop
in any disease that causes pituitary enlargement, including the present
case; however, few studies have reported such
cases3)4) and there are no case reports of visual
impairment alone.